Wednesday, October 24, 2012

Fueling 101: During

Most people know that what we eat on a daily basis plays a big role in our overall energy level and our ability to perform (at work, during exercise, etc.).  We've already discussed some things to do before exercise to make sure you're properly fueled and ready to go.  But what about during workouts?  Proper nutrition during exercise can result in improved performance and enhanced stamina...which are both very good things for athletes!  

So what do you need for exercise lasting longer than 45-60 minutes?  Simply put, we need to replace what we are losing.  So think about it...during prolonged physical activity, your body is losing fluids (sweat), energy (more specifically carbohydrates) and salt (sodium also through sweat).

Finding a good balance between sweat losses and fluid intake is essential to preventing dehydration, cramping and other undesirable outcomes.  The average sweat rate is about 1 liter per hour.  This might sound gross when you quantify it, but it's still important to take note of.  Sweat rate varies with exercise type, intensity, body size, weather conditions and more.  The key is to understand your personal sweat rate.  And guess what?! Figuring out your sweat rate is easy and you can calculate it all by yourself! Start by weighing yourself before and after a long workout (~1hr makes it simple), and determine the weight you lost.  Convert this to ounces (1lb=16 ounces) and add any fluids you took in during the workout.  For example, if you lost one pound over the hour and drank 16 ounces of fluid, your total sweat rate is 32 ounces per hour.  So this is what you should aim to replace!  As a general guideline, start taking fluids around 45-60 minutes into a run and try to take 3-6 ounces every 15-20 minutes.

After the first hour(ish) of exercise, we need to consume about 30-60 grams of carbohydrates per hour (about 120-240 calories).  It doesn't really matter what form these carbs and calories come in.  There are a variety of products, including sports drinks, energy bars, gels, beans, etc that provide calories and carbohydrates for fuel.  Go for whatever is best tolerated by your body and GI tract!  For a lot of people, especially those who are new to eating on the go, this is not easy.  As with most things, practice makes perfect! Experiment with different products BEFORE your event to determine what you feel most comfortable with and practice on long runs!  Also remember to check what products your event will provide on the course and practice with that or plan to BYOF (bring your own fuel)! 

While most people should restrict sodium in their diets, athletes who do this put themselves at risk for electrolyte imbalance leading to cramping, muscle spasms or worse.  As with fluids, sodium excretion can vary person to person.  If you're a "salty sweater", you may notice crusty white salt on your skin or clothes following a workout.  On average, athletes lose around 1,000mg of sodium per hour of exercise, which needs to be replaced.  This can be done through sports drinks, salt packets, tabs or salty snacks.  

So...the takeaway?  For exercise lasting more than one hour, you should be replacing fluids, carbs and salt to maximize performance.  You no doubt are following a training plan for your event, and likely know your projected pace, expected playlist and race day have a nutrition plan as well!  Practice makes perfect!

Up next....Recovery nutrition for AFTER!

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